OWLFileUtils.java

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package edu.tum.cs.ias.knowrob.owl.utils;

import java.io.*;
import org.semanticweb.owlapi.apibinding.OWLManager;
import org.semanticweb.owlapi.model.*;
import org.semanticweb.owlapi.vocab.PrefixOWLOntologyFormat;


public class OWLFileUtils {

        public static OWLOntology loadOntologyFromFile(String filename) throws OWLOntologyCreationException {
                OWLOntologyManager manager = OWLManager.createOWLOntologyManager();
                return manager.loadOntologyFromOntologyDocument(new File(filename));
        }
        
        
        public static boolean saveOntologyToStream(OWLOntology ontology, OutputStream stream, OWLOntologyFormat format) {

                boolean ok = false;

                if (stream != null) {

                        try {

                                // Get hold of the ontology manager
                                OWLOntologyManager manager = ontology.getOWLOntologyManager();

                                // By default ontologies are saved in the format from which they were loaded.
                                // We can get information about the format of an ontology from its manager
                                OWLOntologyFormat currFormat = manager.getOntologyFormat(ontology);

                                if (currFormat.equals(format)) {

                                        // Save a copy of the ontology to the given stream.
                                        manager.saveOntology(ontology, stream);

                                } else {

                                        // Some ontology formats support prefix names and prefix IRIs. When we save the ontology in
                                        // the new format we will copy the prefixes over so that we have nicely abbreviated IRIs in
                                        // the new ontology document
                                        if (format.isPrefixOWLOntologyFormat() && currFormat.isPrefixOWLOntologyFormat()) {
                                                ((PrefixOWLOntologyFormat)format).copyPrefixesFrom(currFormat.asPrefixOWLOntologyFormat());
                                        }
                                        manager.saveOntology(ontology, format, stream);

                                }

                                ok = true;

                        } catch (Exception e) {
                                System.out.println("Could not save ontology: " + e.getMessage());
                        }

                }

                return ok;
        }


        public static String saveOntologytoString(OWLOntology ontology, OWLOntologyFormat format) {

                String s = null;
                ByteArrayOutputStream os = new ByteArrayOutputStream(4096);

                if (saveOntologyToStream(ontology, os, format)) {
                        try {
                                s = new String(os.toByteArray(), "UTF-8");
                        } catch (UnsupportedEncodingException e) {
                                System.out.println("UTF-8 encoding is unsupported: " + e.getMessage());
                        }                       
                }

                return s;

        }



        public static boolean saveOntologyToFile(OWLOntology ontology, OWLOntologyFormat format, String file) {

                boolean ok = false;

                try {
                        ok = saveOntologyToFile(ontology, file, format);                        
                } catch (NullPointerException e) {
                        System.out.println("Could not save ontology: null pointer argument found\n" + e.getMessage());
                }

                return ok; 

        }


        public static boolean saveOntologyToFile(OWLOntology ontology, String file, OWLOntologyFormat format) {

                boolean ok = false;

                try {

                        File f = new File(file);
                        OWLOntologyManager manager = ontology.getOWLOntologyManager();
                        manager.saveOntology(ontology, format, IRI.create(f.toURI()));

                        ok = true;

                } catch (Exception e) {
                        System.out.println("Could not save ontology: " + e.getMessage());
                }

                return ok;
        }


}